The invention relates to a fuel injection pump as defined hereinafter.
A fuel injection pump of this kind has been disclosed, for instance by German Offenlegungsschrift 39 28 613. In this known embodiment, the fuel reservoir is embodied as a diaphragm reservoir and is a component that is flanged laterally to the injection pump housing. This component makes the installed size of the injection pump larger and causes problems if the fuel reservoir is made large. Yet a small fuel reservoir has the disadvantage that in the intake stroke the pressure in the suction chamber drops excessively, which once again impedes the function. Aside from this, flanging the fuel reservoir on the outside creates additional surfaces that must be sealed off from the outside, which in turn increases the danger that fuel may escape at the surface of the injection pump.
The known pump also has a pump piston, which is driven by the cam drive to reciprocate and at the same time rotate. The pump and distributor piston is retained in the process, by its end protruding into the suction chamber, against a roller ring by means of a spring together with a cam disk; because of the motion of the pump piston, the volume of the cam chamber varies periodically, and is associated with periodic, brief changes in pressure, which in the intake stroke are utilized to improve the process of filling the pump work chamber, because the movable wall embodied as a diaphragm is deflected by the pressure pulses toward the cam chamber. The pressures in the suction chamber and in the cam chamber should be approximately equal for that purpose.